1. Field of the Invention
The present invention relates to an A1-killed hot rolled steel sheet having excellent workability and a production method thereof. More particularly the present invention relates to an A1-killed hot rolled steel sheet containing boron and a method for producing a hot rolled steel sheet having excellent cold workabilities.
2. Description of the Prior Art
Conventionally, an A1-killed hot rolled steel sheet has been widely used as a deep-drawing hot rolled steel sheet. However, the A1-killed hot rolled steel sheet has a defect in that it has higher yield point and it is harder as compared with a rimmed steel and a capped steel. For overcoming this defect, it has been proposed to apply a high coiling temperature (for example 700.degree.-720.degree. C) so as to soften the steel and improve the cold workability. Even in this case, as the high coiling temperature is required, the acid pickling efficiency is lowered so that the productivity is greatly lowered, or the high coiling temperature causes the coalescence and coarsening of carbides so that the improvement of the cold workability is partly hindered.